Monobrom derivative of fluorescein



Patented June 30, 1931 UNITED STATES PATENT OFFICE WILLARD L. VOGEL, OFLOS ANGELES, CALIFORNIA, ASSIG-NOR OF ONE-TENTH TO PAUL W. IPRU'TZMANMONOBBOM DERIVATIVE FLUORESCEIN No Drawing. Original application filedMay 28, 1928, Serial No. 281,355. Divided and this application filedSeptember 24, 1929.

tives heretofore known the conversion of the mono-brom compound into adi-mercury derivative, and the conversion of the mercury derivative intosalt of an alkali metal.

The first step is taken in the following manner. To one molecule of 332parts by weight of fluorescein I add approximately 660 parts of glacialacetic acid, bring the fluorescein into even suspension and addgradually one molecule or 160 parts by weight of bromin (Br Copiousfumes of hydrobromic acid are given off and agitation is continued atnormal temperature until these fumes cease. The mixture is now allowedto stand for a short time, or until a pasty yellow cake is formed. Thisoperation must be conducted in glass or equivalent vessel.

I next add to the cake about 1,000 parts by weight of water and stiruntil the cake. is broken up, finally adding and intermixing anadditional 3,200 parts of water. The thick yellow magma thus produced isthen filtered by suction, washed with water, sucked as dry as possible,and finally transferred to a drying dish of porcelain or similarmaterial, over the surface of which it is thinly distributed. Thematerial is then heated on a sand or oil bath to a temperature not toexceed 105 (3., the- Serial No. 394,926.

The yield is approximately 1.1 times the weight of fluorescein taken.The reaction which takes place appears to be represented by thefollowing structural formula, it being understood that I have notdetermined which one of the three possible positions in the resorcinolring is occupied by the bromin.

H H on H H on a a A, 4, B6 on HO 011 116/ on HC OB: Ht o/C G 0 HI) -o lHO\ on nc on n I u 0 I? H OH H OH Fluorescein M. W. 332Monobromfiuorescein M. W. 411 Bromin M. W. 160 Hydrobromic acid W. 81

